The issue isn't the browser itself so much as it's the Service Book entry that you need to have.

The browser that you would get delivered from a third-party BES/MDS will be pre-configured to route your traffic through that MDS (via a Service Book entry from that third-party service).

If you cancel your service with them, they will presumably remove your account from their servers. So, although the browser will still be there, you won't be able to actually go anywhere with it (since it will be trying to route traffic via the BES/MDS where you will no longer have an account).

Basically, you need Cingular to send you the service book entry for their service. I'm not aware of any way around this, unless somebody knows of a way to export an individual service book entry from one Blackberry and import it to another, in which case another Cingular customer who does have this working might be able to help you.

On Rogers, the BWC site has an option under "Profile" to "Send Internet Browsing Service Book". You might want to look for this on the Cingular BWC to see if it's available... (I don't think it's something Rogers added, since the BWC software is somewhat generic, but it may be possible that Cingular turned it off somehow).